Inevitability of the emergence and persistence of genetic parasites caused by evolutionary instability of parasite-free states.

Genetic parasites, including viruses and mobile genetic elements, are ubiquitous among cellular life forms, and moreover, are the most abundant biological entities on earth that harbor the bulk of the genetic diversity. Here we examine simple thought experiments to demonstrate that both the emergence of parasites in simple replicator systems and their persistence in evolving life forms are inevitable because the putative parasite-free states are evolutionarily unstable.

REVIEWERS: This article has been reviewed by Yitzhak Pilpel, Bojan Zagrovic, and Eric van Nimwegen.